package boot.example.tcp.server.utils;

/**
 * 十六进制编码工具类
 * @Author guoyb
 * @Date 2023/10/13  14:01
 */
public class HexStringUtils {

    private static final char[] DIGITS_HEX = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

    /**
     * 编码
     * @param data
     * @return
     */
    protected static char[] encodeHex(byte[] data) {
        int l = data.length;
        char[] out = new char[l << 1];
        for (int i = 0, j = 0; i < l; i++) {
            out[j++] = DIGITS_HEX[(0xF0 & data[i]) >>> 4];
            out[j++] = DIGITS_HEX[0x0F & data[i]];
        }
        return out;
    }

    /**
     * 解码
     * @param data
     * @return
     */
    protected static byte[] decodeHex(char[] data) {
        int len = data.length;
        if ((len & 0x01) != 0) {
            throw new RuntimeException("字符个数应该为偶数");
        }
        byte[] out = new byte[len >> 1];
        for (int i = 0, j = 0; j < len; i++) {
            int f = toDigit(data[j], j) << 4;
            j++;
            f |= toDigit(data[j], j);
            j++;
            out[i] = (byte) (f & 0xFF);
        }
        return out;
    }

    /**
     *  将字符转换为十六进制数值
     * @param ch
     * @param index
     * @return
     */
    protected static int toDigit(char ch, int index) {
        // 用于将指定的字符转换为对应的数值 ,16进制
        int digit = Character.digit(ch, 16);
        if (digit == -1) {
            throw new RuntimeException("Illegal hexadecimal character " + ch + " at index " + index);
        }
        return digit;
    }

    /**
     * 16位字节数组解析为字符串
     * @param bs
     * @return
     */
    public static String toHexString(byte[] bs) {
        return new String(encodeHex(bs));
    }

    /**
     * 字符串转为16位字节数组
     * @param hex
     * @return
     */
    public static String hexString2Bytes(String hex) {
        return new String(decodeHex(hex.toCharArray()));
    }

    public static byte[] chars2Bytes(char[] bs) {
        return decodeHex(bs);
    }

    public static void main(String[] args) {
        String s = "abc你好1212";
        String hex = toHexString(s.getBytes());
        String decode = hexString2Bytes(hex);
        System.out.println("原字符串:" + s);
        System.out.println("十六进制字符串:" + hex);
        System.out.println("还原:" + decode);


        s="77 72 69 74 65 42 79 74 65 73 3A 39 62 37 64 36 37 34 36";


    }
}
